The tubs I buy are 15 or 16 kg (I forget) and I allow 1 tub per 3 - 4 sq metres to allow for dodgy walls (yes I know it says on the tub that it does up to 10 sq metres, but I've never experienced that - it never goes that far). But at £6-£7 for a tub of Dunlop adhesive that ain't too bad. Especially when you compare it to the price of BAL flexible adhesive, that works out at around £10 per sq metre! (for tiling onto wooden floors)
I'd say your plumber isn't taking the **** to be honest. Having said that, if your wall is as flat as a billiard table then I'd have expected it to go a little further than 2 metres.

The tubs I buy are 15 or 16 kg (I forget) and I allow 1 tub per 3 - 4 sq metres to allow for dodgy walls (yes I know it says on the tub that it does up to 10 sq metres, but I've never experienced that - it never goes that far). But at £6-£7 for a tub of Dunlop adhesive that ain't too bad. Especially when you compare it to the price of BAL flexible adhesive, that works out at around £10 per sq metre! (for tiling onto wooden floors)
I'd say your plumber isn't taking the p**s to be honest. Having said that, if your wall is as flat as a billiard table then I'd have expected it to go a little further than 2 metres.

Coverage will depend on the size of notch on your plumbers trowel, are they a large format tile as that will require a bigger notch but if they are that large you should really be using a cement based adhesive not ready mixed.

How very polite of you Zampa. How can you say that if you know nothing of my skill level? You are correct that I'm not a time served decorator or tiler (I'm actually a time served Instrument Mechanic), but does that mean that I can't paint or tile well?
I fit bathrooms, kitchens, do plumbing, lay flags, tile walls and floors, paint, joinery and I also do computer repairs and upgrades. Most of my customers say that it's great that they've found someone they can trust to do all their jobs for them. It's more convenient for them to have me do the whole job than having to arrange to get several tradesmen in to do it.
Are you implying that I can't earn a living in any field that I'm not time served in? If so, why?
As long as there's a market for what I'm doing (and it's still worth it financially) then I'll continue to do it. If that's alright with you.

Communicating over the internet is fraught with risk because so much of our communication is non-verbal.

The correct interpretation of a spoken word depends not only on the actual words used, but the tone of voice with which we speak, the look in our eye and the expression on our face when we speak, our own assessment of the intent of the speaker in making his statements, and even the age and apparent sobriety of the person speaking. We take all of these things into account to correctly interpret what someone says.

But all of that non-verbal information is missing when communicating over the internet, so it's very easy to both misinterpret and be misinterpreted.

So, when someone says something half seriously over the internet, it's safest to presume the serious content is much closer to 0 percent than it is to 100 percent. Or, at least, until the serious content can be more accurately determined.

As a landlord, I have to be at least competent in a wide variety of trades and professions to do my job well. I'm not as competent in each trade or profession as the professionals, but I have a higher level of competence in a wider variety of trades and professions than most professionals. And, let's face it guys, most of the problems we encounter in and around our homes don't require years of experience to understand or solve. They just require a willingness to try giving it your best shot before giving up. Usually, that's all it takes.

I think it best to put the in the same bag as the rest of non-verbal communication.

For example, I make my own wine. I have a magic fridge with two stainless steel cylinders in it and one cast steel cylinder. The stainless steel cylinders contain home made wine. The cast steel cylinder contains CO2 at 700 psi pressure. That fridge magically converts home made wine into home made champagne for me.

So, when I post, most of the time I'm totally plastered.

Good thing all those non-verbal cues are missing. Otherwise no one would bother reading my posts! I mean, how attentively to you listen to someone passed out face down on a city sidewalk during the day.